Hybrid-electric propulsion systems may provide certain efficiency benefits for aircraft, such as commercial passenger aircraft. Certain hybrid electric propulsion systems include an electric power source providing electricity to an electric propulsor. The electric propulsor may generally include an electric motor and a propulsor, with the electric motor driving the propulsor. One issue with utilizing an electric propulsor, however, is ensuring a maximum efficiency and/or power density of the electric motor. Accordingly, a hybrid-electric propulsion system including an electric motor designed to have a desired power density, and further to operate efficiently with an aircraft within which it is installed would be useful.